The present invention relates to a method of packaging a rectangular moulded chocolate bar having a predetermined thickness, an upper face and a bottom face and bevelled longitudinal and lateral side faces, with heat sealable composite multilayer material.
Chocolate bars are usually packaged in a first package consisting for example of a multilayer sheet, in which one layer may be an aluminum film, which is either heat sealable or not, folded by an appropriate mechanism, known as such, and then in a second package consisting of a banderole or a printed paper label. This method, which has become conventional, continues to be used on a very large scale. However, it necessitates installations for supplying and folding at least two different packing materials. This type of packaging moreover does not necessarily meet the criterion of inviolability.
Chocolate bar packaging machines with a single operation have been developed, using one or several packaging materials folded simultaneously in a folding box. This type of package is neither sealed, nor inviolable.
Thus, at present, only cumbersome and costly machines with two operations are capable of achieving a sealed and inviolable package for chocolate bars presenting a conventional appearance. It is to be noted that chocolate bars, which have generally a thickness of about 7-12 mm, have to be packaged in a manner which respects the well known traditional packaging appearance having lateral folds and a bottom recovering flap having a trapezoidal shape. The lateral folds are necessary for getting rectilinear folding lines along the intersection lines of the adjacent bevelled side faces. These requirements are specific to chocolate bars which are usually moulded and have therefore a predetermined thickness of at least 7 to 12 mm and bevelled side faces which permit the withdrawal from the mould.
U.S. Pat. No. 2,449,334 disclosed a method for packaging a flat stick of chewing-gum with a sheet of a sealable material. It is to be noted that chewing-gum sticks have a very small thickness, of about 2 mm, and have generally rectangular side faces which are substantially perpendicular to the bottom and top flat faces of the stick. In these conditions, there is no need and it would even not be possible to provide folds presenting rectilinear folding lines on the intersection lines of two adjacent side faces.